This invention relates to a magnetic angular position sensor which may be used as a compass, an inclinometer or a proximity detector.
It is known to make a cheap compass, such as is sold as a car accessory, using a neutrally buoyant magnet assembly in a transparent compass chamber. The magnet assembly is traditionally combined with a compass card and the chamber is filled with a transparent fluid, e.g. alcohol. Because the compass card is floating freely in the chamber there is occasional friction between the card and the chamber wall.
More complex is the gimballed compass using a weighted mechanical system to hold a pivoted magnetic compass card horizontally regardless of the orientation of the outer casing. The position of the compass card is read using light sensors and an encoded disc and the positional information is relayed electrically to the outer casing, usually via slip-rings. Such a compass is an expensive item and is usually found in marine navigation apparatus.
There are also under development other compasses using the Sagnac effect in fibre optic loops.